]STew York Agricultural Experiment Station. 283 



remove the magnesium chloride formed in neutralization. The 

 dialyzed solution was evaporated to dryness and finally dried at 

 120° C. 



Analysis of the material showed it to contain 1.06 per ct. Mg 

 (equal to 1.76 per ct. MgO). Calculated to correspond with basic 

 calcium caseinate (containing 1.78 per ct. Ca or 2.50 per ct. CaO), 

 this compound should contain 1.08 per ct. Mg (equal to 1.80 per ct. 

 MgO). Expressed in another form, our results indicate that 1 gram 

 of casein combines with 8.72 x 10- 4 gram equivalents of magnesium 

 (theoretical, 9 x 10- 4 ). 



This compound is basic magnesium caseinate, the casein being octo- 

 valent. The compound is easily soluble in water, its solution being 

 neutral to phenolphthalein. It is also soluble in a 5 per ct. solution 

 of NaCl. 



PREPARATION and composition of neutral magnesium caseinate. 



Base-free casein was dissolved in a solution of magnesium hydroxide 

 containing an excess of magnesium oxide in suspension. The 

 mixture was filtered and the filtrate was made nearly neutral to 

 litmus with N /io HC1. The solution was dialyzed and then made 

 neutral to litmus with N /io HC1; the end-point was determined by 

 adding the acid slowly, until both red and blue litmus paper could be 

 left in the solution several minutes without change of color in either. 

 The solution was then dialyzed again and the casein precipitated 

 with acid-free alcohol; the mixture was then filtered, and the precipi- 

 tate was washed thoroughly and was finally dried at 120° C. 



Determination of the magnesium in this preparation gave 0.71 

 per ct. Mg (equal to 1.18 per ct. MgO). Calculated to correspond 

 with neutral calcium caseinate (containing 1.10 per ct. Ca or 1.55 

 per ct. CaO), this compound should contain 0.67 per ct. Mg (equal 

 to 1.12 per ct. MgO). Expressed in another form, our results in- 

 dicate that 1 gram of casein combines with 5.84 x 10- 4 gram 

 equivalents of magnesium (theoretical 5.625 xlO- 4 ). 



This compound is neutral magnesium caseinate, the casein being 

 penta-valent. The compound is easily soluble in water and in a 5 

 per ct. solution of NaCl. 



preparation and composition of di-magnesium caseinate. 



Solution of base-free casein in magnesium hydroxide containing 

 an excess of magnesium oxide is effected in the manner already 

 described. To the filtered solution, N /so HC1 is added until near the 

 point of precipitation, as shown by a preliminary test (Technical 

 Bulletin No. 26, pp. 15-17). The solution is then dialyzed. 

 Alternate addition of acid and dialysis are repeated several times, 

 until the addition of a small amount of acid to a test portion causes 

 precipitation. The amount of acid necessary for complete pre- 



